1. Field of the Invention
The present invention pertains to component shielding. More specifically, the present invention pertains to the shielding of electrical components and circuits that radiate, or are sensitive to, electromagnetic interference (EMI).
2. Discussion of Related Art
Isolation of circuit components from sources of EMI is particularly important in communications equipment, such as cellular telephone units and related relay-station equipment, having components that operate in the 50 MHz to 4 GHz frequency range. The typical rf isolation shield for electronic components in such units cannot provide the substantial shielding they require, greater than 60 dBm, without pressure-fit conductive gaskets and a large number of screws, or soldering. More than one screw for each linear inch may be required at 1000 MHz to sufficiently ground and stably secure shield walls.
Alternatively, if the shield is formed as a cap, the cap may be attached and grounded by soldering. But soldering is also expensive, and it may be less reliable than gasket mounting after a cap is removed, because air gaps in the rf seal, caused by the roughness of the solder from which the cap was removed, may remain after the cap is reattached by soldering. Moreover, such caps may be difficult to unsolder and the unsoldering operation itself is risky, possibly causing heat damage to electronic components or delamination of portions of the assembly. Furthermore, even the gaskets tend to leak when they are reinstalled, because of mechnical damage to the thin gasket material or an improper placement of the gasket material during reassembly causing EMI leakage. A new gasket may be needed each time the shield is reassembled.